1. Field of the Invention
The present invention generally relates to an improved lens barrel having a plurality of lens groups capable of changing its states between a collapsed state in which at least one portion of the lens groups is collapsed within a main body of a camera and a photographing state in which the at least one portion of the lens group is extended toward an subject to be photographed. The present invention also relates to a camera and mobile information terminal device having such lens barrel.
The lens barrel is preferably used for a zoom lens wherein a plurality of lens groups thereof are moved relatively each other so that the zoom lens can change its focal length.
2. Background Art
Conventionally, in an imaging device such as a digital camera, with advance in a high performance of a photographing lens such as a zoom lens, or miniaturization of the imaging device according to the user's demand, there has been increasingly used a lens barrel wherein telephoto cylinders are collapsed in a main body of a camera when photographing is not carried out.
Furthermore, because of the demand for further reduction in thickness of a main body of a camera (imaging apparatus), it is now important to reduce the thickness of the telescopic lens cylinders in a collapsed position to the maximum extent.
As a technology to cope with the demand for reduction in thickness of the main body of the camera, there has been disclosed structures wherein a telescopic cylinder retaining therein a plurality of lens groups is collapsed into the imaging device when not in use, and one of the lens groups is retracted out of an optical axis of the lens groups when the lens groups are collapsed.
According to the conventional structures, since one of the lens groups is retracted out of an optical axis of the lens groups when the lens groups are collapsed, the entire dimension of the telescopic cylinder in a direction of the optical axis can be reduced, so that the thickness of the camera (imaging device) can be reduced (See, e.g., Japan Patent Application Laid-Open Nos. 2003-315861, 2003-149723).
However, further miniaturization, especially in further reduction in thickness of the main body of the camera has been demanded.